S'Ah^ 

BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


NO.  434 

Science  Series,  Vol.  4,  No.  3,  pp.  39-30. 


ON  THE  ADDITION  OF  ORGANIC  ACIDS  TO 
UNSATURATED  HYDROCARBONS 


BY 

ARTHUR  F.  SIEVERS 


A  THESIS  PRESENTED  FOR  THE  DEGREE  OF  BACHELOR  OF  SCIENCE 
THE  UNIVERSITY  OF  WISCONSIN 

1909 


CONTRIBUTIONS  FROM  THE  COURSE  IN  PHARMACY 


MADISON,  WISCONSIN 
July,  1911 
PRICE  20  CENTS 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


Entered  as  second-class  matter  June  10, 1898,  at  the  post  office  at  Madison,  Wisconsin 
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BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


NO.  434 

Science  Series,  Vol.  a,  No.  3,  pp,  39-30. 


ON  THE  AUDITION  OF  ORGANIC  ACIDS  TO 
UNSATURATED  HYDROCARBONS 


ARTHUR  F.  SIEVERS 


A  THESIS  PRESENTED  FOR  THE  DEGREE  OF  BACHELOR  OF  SCIENCE 
THE  UNIVERSITY  OF  WISCONSIN 

1909 


CONTRIBUTIONS  FROM  THE  COURSE  IN  PHARMACY 


MADISON,  WISCONSIN 
June,  1911 


z-v 

TABLE  OF  CONTENTS 


Page 


I.  Introduction .  5 

II.  The  addition  of  glacial  acetic  acid  to  pinene .  9 

III.  The  addition  of  glacial  acetic  acid  to  limonene .  12 

IV.  Formation  of  esters  at  higher  temperature  and  underpressure  22 

V.  Formation  of  esters  under  ordinary  pressure  and  at  boiling 

temperature .  25 

VI.  Addition  of  picric  acid  to  pinene .  26 

VII.  Addition  of  glacial  acetic  acid  to  amylene .  29 

VIII.  Generalizations .  30 

IX.  Observations  and  conclusions  after  two  and  one  half  years..  34 

X.  Bibliography .  38 


Digitized  by  the  Internet  Archive 
in  2017  with  funding  from 

University  of  Illinois  Urbana-Champaign  Alternates 


https://archive.org/details/onadditionoforgaOOsiev 


ON  THE  ADDITION  OF  ORGANIC  ACIDS  TO 
UNSATURATED  HYDROCARBONS 


INTRODUCTION 

With  the  exception  of  the  polymerization  of  acetylene  and  its 
homologues,  no  systematic  study  appears  to  have  been  made  of 
the  additive  capacity  of  unsaturated  hydrocarbons  in  so  far  as 
other  carbon  compounds  are  involved. 

Inasmuch  as  a  number  of  observations  and  experiments,  that 
have  been  made  in  this  laboratory  from  time  to  time,  have  led 
up  to  the  present  systematic  study  of  this  subject,  the  more 
significant  ones  may  here  be  recorded : 

In  1894  Mayer  1  made  some  observations  on  the  angle  of  rota¬ 
tion  of  limonene  in  various  optically  inactive  solvents.  He  drew 
the  following  conclusions  from  his  results :  “  It  is  apparent  that 
the  solvents  employed,  viz. :  absolute  and  ordinary  alcohol,  chloro¬ 
form  and  glacial  acetic  acid,  diminish  the  rotary  power  of 
limonene.  In  the  case  of  absolute  alcohol  and  chloroform  the 
rotatory  power  of  the  limonene  seems  to  decrease  with  fair  reg¬ 
ularity  as  the  quantity  of  solvent  increases.  In  the  case  of 
glacial  acetic  acid  no  such  regularity  is  apparent.” 

These  observations  were  pursued  somewhat  farther  by  Schrei¬ 
ner  and  Neumann.2  Inasmuch  as  the  results  obtained  have  never 
been  published,  some  of  them  may  here  be  recorded.  The  ex¬ 
periments  were  begun  by  Neumann  during  the  academic  year 
1900-1901,  redeterminations  being  made  by  Schreiner  in  1902. 
While  the  seal  of  most  of  the  bottles  in  which  these  solutions 
were  kept  had  been  injured,  some  of  them  were  still  perfect. 


1  Am.  Chem.  Journ.,  17,  p.  692. 

2  E.  C.  Neumann  :  Thesis  submitted  for  the  degree  of  Graduate  in  Pharmacy 
V.  W.,  1901. 

[43] 


6 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


It  was  possible  therefore  to  supplement  the  observations  of  Neu¬ 
mann  extending  over  but  a  few  months  by  observing  the  angle 
of  rotation  after  a  lapse  of  five  years.  This  was  done,  and  the 
following  data  were  obtained,  which,  for  the  sake  of  comparison, 
are  placed  side  by  side  with  those  obtained  by  Neumann  and 
Schreiner. 


Solution 

1901 

1902 

1907 

Pure  Limonene . 

104.80 

102.00 

104.60 

Limonene  +  acetone . 

36.50 

35.00 

35.10 

Limonene  +  chloroform . 

37.14 

35.90 

35.90 

Limonene  4-  ether . 

36.80 

34.30 

33.66 

Limonene  +  alcohol . 

32.30 

32.60 

28.20 

Limonene  +  glacial  acetic  acid . 

34.90 

35.40 

36.40 

Turpentine  oil  +  absolute  alcohol . 

6.71 

6.80 

6.00 

In  1897,  at  a  time  when  the  method  of  assaying  alcoholic  com¬ 
ponents  of  volatile  oils  by  the  acetylization  method  had  come 
into  general  use,  Professor  Kremers  became  interested  in  the 
problem  of  the  influence  of  the  unsaturated  hydrocarbons  present 
on  the  result  of  the  assay.  Even  if  it  were  not  regarded  probable 
that  the  acetic  acid  anhydride  used  in  the  assay  should  add  to 
the  hydrocarbon,  acetic  acid  might,  as  had  indeed  been  shown.3 
Inasmuch  as  most  volatile  oils  contain  some  moisture  the  con¬ 
version  of  at  least  a  small  part  of  the  acetic  acid  anhydride  to 
anhydrous  acetic  acid  could  be  explained.  In  oils  rich  in  alcohol 
such  a  change  might  become  the  cause  of  an  insignificant  error, 
but  how  in  oils  with  but  a  low  alcohol  content? 

With  such  a  priori  conceptions,  the  results  obtained  by  actual 
tests  were  astounding.  Preliminary  experiments  were  made  with 
limonene,  pinene  and  caryophyllene.  A  mixture  of  10  cc  of  the 
hydrocarbon,  10  cc  of  acetic  acid  anhydride  and  2  gms.  of  an¬ 
hydrous  sodium  acetate  were  heated  for  one  hour  and  then 
treated  according  to  the  usual  acetylization  method.  The  results 
obtained  by  Martha  M.  James  at  that  time  are  herewith  re¬ 
corded  : 


3  Bouchardat  et  Lafont,  Compt.  rend.j  102,  p.  171. 


[44] 


SIEVERS — ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  7 


Description  of  hydrocarbon 

Amount  of  ester  calculated 
asC10  H17  O.COCH3 

I 

II 

Limonene  from  oil  of  Sweet  Orange.  Fraction  174°-176° 

29.35 

29.1 

Turpentine — commercial,  crude . 

4.0 

3.8 

Turpentine,  rectified  . 

3.9 

3.6 

Turpentine — rectified  and  dried  with  calcium  chloride.. 
Turpentine — rectified,  dried  with  calcium  chloride  and 

2.4 

2.7 

fractionated  (150°-156°) . 

3.3 

These  results  were  so  striking  that  they  were  stated  to  Dr. 
C.  Kleber  and  Dr.  Best  during  the  summer  of  1896  while  Pro¬ 
fessor  Kremers  was  in  the  factory  of  Fritzsche  Bros,  at  Garfield, 
for  the  purpose  of  studying  some  of  the  practical  problems  that 
presented  themselves  in  the  revision  of  the  U.  S.  P.  tests  on 
volatile  oils.  These  gentlemen  were  naturally  skeptical,,  but 
their  curiosity  was  sufficiently  roused  to  test  the  matter.  Hav¬ 
ing  on  hand  a  carefully  fractionated  pinene  prepared  some 
months  previously  and  kept  in  a  cool  dark  cellar,  Dr.  Best  ob¬ 
tained  results  much  higher  than  those  obtained  by  Miss  James 
for  the  same  hydrocarbon. 

Not  satisfied,  Professor  Kremers  requested  Mr.  J.  A.  Ander¬ 
son  to  repeat  some  of  the  experiments  previously  made  by  Miss 
James.  His  results  are  herewith  recorded: 


Description  op  Hydrocarbon 

Amount  of  Ester  Calcu¬ 
lated  as  Ci  oHi  7O.COCH3 

I 

II 

Limonene  —  fraction  174°-178° . 

50.16 

49.5 

Limonene  —  fraction  176°-178° . 

62.7 

05.2 

Turpentine  oil  —  crude . 

7.51 

7.33 

Before  proceeding  to  record  the  results  of  more  systematic 
experimentation,  it  will  be  necessary  briefly  to  review  the  work 
that  has  thus  far  been  recorded  on  this  subject.  The  results 
found'  may  be  briefly  summarzied  by  tabulating  the  unsaturated 
hydrocarbons  and  the  organic  compounds  that  have  been  added 
to  each  of  these. 


[45] 


3  BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 

PlNENE 

I.  Alcohols 

1)  Trinitrophenol 

II.  Aldehydes 

1)  Formaldehyde 

III.  Acids 

1)  Acetic  acid 

2)  Benzoic  acid 

3)  Oxalic  acid 

Limonene  and  Dipentene 

I.  Alcohols 

II.  Aldehydes 

1)  Formaldehyde 

III.  Acids 

Camphene 

I.  Alcohols 

II.  Aldehydes 

III.  Acids 

1)  Formic  acid 

2)  Acetic  acid 

Fenchene 

I.  Alcohols 

1)  Ethyl  alcohol 

II.  Aldehydes 

III.  Acids 

1)  Acetic  acid 

If,  finally,  it  be  borne  in  mind  that  some  of  the  processes  pat¬ 
ented  for  the  semi-artificial  preparation  of  camphor  involve  the 
addition  of  organic  acids  to  the  pinene  of  turpentine  oil,  it  must 
become  apparent  that  there  exist  abundant  reasons,  both  purely 
theoretical  as  well  as  practical,  which  seem  to  demand  a  careful 
and  systematic  study  of  the  entire  problem  of  the  addition  of  or¬ 
ganic  compounds,  more  particularly  of  organic  acids,  to  unsat- 

[46] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  $ 


urated  hydrocarbons.  A  beginning  has  been  made  and  the  re¬ 
sults  thus  far  obtained  not  only  justify  the  time  spent  on  this 
problem,  but  invite  a  much  more  extensive  investigation  of  the 
entire  field. 


THE  ADDITION  OF  GLACIAL  ACETIC  ACID  TO  DEXTRO 

PINENE 

The  pinene  used  in  the  following  experiments  was  obtained 
from  commercial  American  oil  of  turpentine.  The  oil  was  first 
rectified  by  shaking  with  an  aqueous  solution  of  caustic  potash 
and  subsequent  distillation.  The  first  three-fourths  of  the  oil 
thus  rectified  were  then  fractionated  into  five  fractions  and  the 
specific  gravity  and  angle  of  rotation  of  the  three  pinene  frac¬ 
tions  taken.  The  results  of  the  fractionation  are  herewith  tab¬ 
ulated. 


Fraction 

(D)2o° 

(ar)20° 

1.  —155° . 

2.  155°— 156° . 

0.8560 

0.8564 

0.8585 

+15°  50' 

+14°  14' 

+11°  41' 

3.  156°— 157° . 

4,  157°— 160° . 

5.  160°+ . 

For  the  following  experiments  fractions  2  and  3  were  used. 
They  were  mixed  and  their  physical  constants  retaken.  These 
were  found  to  be  as  follows:  Sp.  gr.  at  20°  C.  0.8575;  angle  of 
rotation  at  20°  C  +  15°  O'. 

500  cc.  of  this  pinene  mixture  were  mixed  with  an  equal  volume 
of  glacial  acetic  acid.  At  the  same  time  another  500  cc.  of  the 
pinene  were  mixed  with  two  volumes  of  glacial  acetic  acid.  The 
physical  constants  of  both  mixtures  were  immediately  taken. 
After  that  the  constants  were  taken  every  ten  days  for  some  time, 
but  the  changes  were  so  small  that  they  were  finally  taken  only 
once  a  month. 


[47] 


10 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


TABLE  I 

1  Volume  of  Pinene  +  1  Volume  of  Acid 


Date 

(D)20o 

(a) 

20° 

Ester  No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

1906 

Aug-.  27 . 

0.9400 

4-8°  41' 

Sept.  21 . 

0.9400 

+8°  35' 

Oct.  5 . 

0.9430 

4-8°  14' 

Oct.  12 . 

0.9428 

4-8°  15' 

Oct.  22 . 

0.9457 

4-7°  35' 

Nov.  1 . 

0.9450 

4-7°  50' 

3.92 

1.36 

2.09 

Nov.  11 . 

0.9454 

+7°  40'. 

Nov.  21 . 

0.9463 

4-7°  54' 

Dec.  3 . 

0.9464 

+7°  32' 

Dec.  13 . 

0.9460 

+7°  45' 

6.26 

2.18 

3.32 

1907 

Jan.  3 . 

0.9477 

4-7°  30' 

Jan.  13 . 

0.9477 

+7°  20' 

8.75 

3.06 

4.69 

Feb.  13 . 

0.9480 

+7°  10' 

9.97 

3.49 

5.46 

Mar.  15 . 

0.9497 

4-7°  12' 

10.85 

3.79 

5.82 

Apr.  16 . 

0.9500 

4-7°  20' 

8.15 

2.86 

4.36 

May  15 . 

0.9502 

+7°  18' 

13.80 

4.84 

7.40 

TABLE  II 


1  Volume  of  Pinene  +  2  Volumes  of  Acid 


Date 

<DV 

O 

! 

Ester  No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

1906 

Aug-  27 

0.9744 

0.9744 

0.9757 

0.9757 

0.9767 

0.9769 

0.9770 

0.9789 

0.9783 

0.9785 

0.9797 

0.9788 

0.9795 

0.9814 

0.0806 

0.9804 

4-6°  8' 
+6°  6' 
+5°  38' 
+5°  15' 
+4°  50' 
+4°  50' 
+4°  47' 
+4°  45' 
+4°  46' 
4-4°  35' 

+4°  28' 
4-4°  30' 
+4°  20' 
4-4°  17' 
4-4°  18' 
+4°  15' 

Sept  21 

Oct  5 

Oct.  12 . 

Oct  22 

Nov.  1. 

3.62 

1.27 

3.03 

. <; . 

Nov  11 

Nov  21 

Dec.  3  . . 

Dec.  13 . 

5.80 

2.03 

4.83 

1907 

Jan  3 

.Ta,n.  13 . 

7.46 

7.94 

8.87 

9.15 

10.87 

2.61 

2.78 

3.10 

3.20 

3.80 

6.27 

6.58 

7.41 

7.60 

9.05 

Feb.  13 . 

Mar.  13 . 

April  16 . 

May  15 . 

[48] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS 


[49] 


T/me  /n  Months 


12 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


THE  ADDITION  OF  GLACIAL  ACETIC  ACID  TO  DEX- 
TRO  LIMONENE 

Preparation  of  Material 

The  limonene  used  in  the  following  work  was  received  through 
the  liberality  of  Dr.  S.  H.  Baer,  at  that  time  with  Mergentine  & 
Lamm  of  New  York,  who  had  obtained  it  as  by-product  in  the 
preparation  of  a  concentrated  oil  of  orange  from  a  crude  oil  of 
orange. 

The  specific  gravity  in  1906  was  0.8530  at  20°  C.;  the  angle 
of  rotation  +  87°  45'  at  20°  C.;  saponification  number  11.84, 
and  acetylization  number  26.6. 

A  small  portion  of  the  material  was  reserved.  The  bulk  of 
the  crude  limonene  was  subjected  to  a  thorough  purification. 
It  was  first  shaken  several  times  with  several  portions  of  sodium 
acid  sulphite  solution  to  remove  any  aldehydes.  However  the 
odor  of  the  limonene  underwent  no  perceptible  change  due  to 
this  treatment.  In  order  to  determine  whether  any  traces  of 
aldehyde  had  been  removed,  the  sulphite  solution  was  neutralized 
with  an  excess  of  sodium  carbonate  and  distilled.  The  distillate 
had  a  very  decided  odor  of  citronellal.  In  order  to  get  a  positive 
test  for  aldehyde  the  distillate  and  also  the  residue  were  shaken 
out  with  ether  separately  and  the  ethereal  solutions  mixed.  These 
upon  evaporation  left  a  small  quantity  of  a  heavy,  syrupy,  brown 
liquid  which  gave  a  positive  test  for  aldehyde  with  magenta 
solution. 

After  the  removal  of  the  aldehydes  the  sp.  gr.  was  found  to 
be  0.8562  at  20°  C.;  the  angle  of  rotation  +  92°  47'  at  20°  C.; 
and  the  saponification  number  6.9  and  6.23  respectively. 

Since  the  saponification  number  of  the  limonene  indicated  an 
appreciable  quantity  of  esters,  it  was  deemed  best  to  saponify 
the  entire  quantity.  The  necessary  quantity  of  caustic  potash 
calculated  from  the  saponification  number  was  dissolved  in  al¬ 
cohol  and  mixed  with  the  limonene.  The  mixture  was  then 
boiled  on  a  water  bath  for  two  hours.  After  cooling  the  limonene 
was  distilled  over  with  steam.  A  perfectly  clear,  colorless  prod- 

[50] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  13 


net  was  obtained  whereas  the  crude  product  had  been  decidedly 
yellow. 

The  constants  of  the  limonene  thus  rectified  were  found  to  be : 
sp.  gr.  0.8440  at  20°  C. ;  angle  of  rotation  +96°  37'  at  20°  C.; 
acetylization  number  10.1. 

The  rectified  limonene  was  fractionated  into  four  fractions. 
The  specific  gravity  and  the  angle  of  rotation  were  taken  of  each 
fraction.  The  following  tabulation  gives  a  summary  of  the  frac¬ 
tionation,  the  constants,  and  the  volume  of  each  fraction. 


Fraction 

Volume  in  cc 

<DV 

(<*)2o° 

—  175°  . 

88 

0.8413 

+93°  49' 

175°  — 176.5° . 

1108 

0.8434  , 

+98°  15' 

176°  — 180° . 

476 

0.8455 

+98°  51' 

180°+ . 

74 

0.8723 

+81°  0' 

For  the  sake  of  better  comparisons  the  data  obtained  in  the 
several  experiments  described  above  are  herewith  tabulated 
again : 


Description  of  limonene 

<DV 

O  1 

© 

s 

Sap.  No. 

Ester  No. 

Crude . 

0.8530 

+87°  45' 

11.45 

26.6 

Shaken  out  with  NaHSC>3  .... 

0.8562 

+92°  47' 

6.56 

Saponified . 

0.8440 

+96°  37' 

4.0* 

10.1 

Fraction  — 175° . 

0.8413 

+93°  49' 

3.16* 

Fraction  175°— 176.5° . 

0.8434 

+98°  15' 

2.65* 

7.6 

Fraction  176.5°-180° . 

0.8455 

+98°  51' 

1.30* 

14.4 

Fraction  180°+ . 

0.8723 

+81°  0' 

5.06* 

51.00 

*  Determinations  made  five  weeks  after  rectification  and  fractionation. 


Formation  of  the  Esters 

In  the  experiments  which  follow  the  limonene  from  fraction 
175°-176.5°  was  used.  The  object  was  to  ascertain  the  rate  of 
ester  formation  of  the  limonene  with  the  glacial  acetic  acid,  and 
the  extent  to  which  this  formation  is  indicated  by  the  specific 
gravity  and  the  angle  of  rotation  of  the  mixture. 

Two  different  mixtures  of  the  limonene  and  the  glacial  acetic 
acid  were  made.  The  first  mixture  consisted  of  one  volume  of 
limonene  and  one  volume  of  glacial  acetic  acid.  The  second  mix- 


[51] 


14 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


ture  consisted  of  one  volume  of  limonene  and  two  volumes  of  the 
acid. 

To  determine  the  effect  of  so-called  catalytic  agents  on  the  rate 
of  ester  formation  in  these  mixtures,  four  more  mixtures  were 
made,  two  containing  hydrogen  chloride  and  two  anhydrous 
sodium  acetate. 

The  two  mixtures  containing  sodium  acetate  were  prepared 
as  the  previous  ones,  namely:  one  containing  equal  volumes  of 
limonene  and  glacial  acetic  acid  and  the  other  containing  one 
volume  of  limonene  to  two  of  the  acid.  To  each  of  these  mix¬ 
tures  were  then  added  exactly  2.5  gins,  of  anhydrous  sodium 
acetate  and  the  mixtures  agitated  frequently  until  the  acetate 
was  dissolved. 

Two  more  mixtures  were  prepared  to  each  of  which  were 
added  the  molecular  equivalent  of  2.5  gms.  of  anhydrous  sodium 
acetate  or  1.11  gms.  of  hydrogen  chloride.  In  all  these  mixtures 
great  care  was  taken  to  prevent  any  admixtures  of  traces  of 
moisture.  It  was,  therefore,  necessary  to  add  the  hydrogen 
chloride  in  some  anhydrous  form  and  not  in  the  form  of  the 
ordinary  aqueous  test  solution.  The  method  adopted  was  as 
follows:  Hydrogen  chloride  was  generated  from  common  salt 
with  sulphuric  acid  and  passed  first  through  a  wash  bottle  con¬ 
taining  sulphuric  acid,  and  then  through  a  bottle  with  calcium 
chloride.  The  gas,  which  after  this  treatment  was  regarded  as 
dry,  was  then  passed  into  glacial  acetic  acid.  The  percentage  of 
hydrogen  chloride  in  the  acid  was  then  determined  gravimet- 
rically  with  silver  nitrate  as  insoluble  silver  chloride. 

A  quantity  of  this  acid  containing  exactly  1.11  gms.  of  hyd¬ 
rogen  chloride  was  weighed  off,  diluted  to  the  desired  volume  and 
mixed  with  the  limonene  as  in  the  previous  mixtures. 

The  specific  gravity  and  angle  of  rotation  of  these  mixtures 
were  taken  immediately  after  they  had  been  mixed  and  after 
that,  with  as  much  regularity  as  possible,  at  intervals  of  ten  days. 
The  changes  found  in  the  constants  in  ten  days  were  so  small, 
however,  that  they  were  finally  taken  only  once  a  month.  Once 
during  each  month  of  observation  the  amount  of  ester  formed 
was  determined  by  means  of  the  acetvlization  number. 

In  determining  the  acetylization  number  considerable  difficulty 

[52] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS 

was  met  with  at  first  due  to  the  strong  acetic  acid  solution.  After 
considerable  experimentation  the  following  method  was  found  to 
give  very  accurate  results:  About  8  gms.  of  the  mixture  are 
weighed  carefully  and  then  transferred  to  a  250  cc.  flask  and  a 
few  drops  of  phenolphthalein  added.  An  alcoholic  potassium 
hydroxide  solution  containing  about  50  gms.  of  potassium  hy¬ 
droxide  to  the  liter  is  then  added  slowly  to  neutralize  the  acetic 
acid.  The  flask  must  be  kept  carefully  cooled  during  the  ad¬ 
dition  of  the  alkali  in  order  to  prevent  the  decomposition  of  any 
esters  due  to  a  rise  in  temperature.  When  exactly  neutral,  10 
cc.  of  a  standard  alcoholic  potassium  hydroxide  solution  are 
added  and  the  mixture  boiled  for  half  an  hour  on  a  water  bath. 
After  cooling  the  excess  of  alkali  is  titrated  back  with  %  N. 
Sulphuric  Acid  V.  S. 


[53] 


16 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


TABLE  I 

1  Volume  of  Limonene  4-  1  Volume  of  Acid 


Date 

(D)20° 

Ester 

No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

Nov.  29,  1906 . 

0.9380 

+47°  30' 

Dec.  8,  1906 . 

0.9384 

+47°  45' 

Dec.  18,  1906 . 

0.9390 

+47°  33' 

Jan.  4,  1907 . 

0.9388 

+47°  10' 

1.84 

0.64 

1.00 

Feb.  12,  1907 . 

0.9390 

+47°  45' 

3.35 

1.17 

1.80 

Mar.  15,  1907, . 

0.9392 

+47°  32' 

3.37 

1.18 

1.82 

Apr.  15,  1907 . 

0.9398 

+47°  30' 

3.86 

1.35 

2.09 

May  15,  1907 . 

0.9400 

+47°  0' 

3.81 

1.33 

2.06 

TABLE  II 

1  Volume  of  Limonene  +  2  Volumes  of  Acid 


Date 

(D)20° 

Ester 

No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

Nov.  29,  1906 . 

0.9733 

+31°  52' 

Dec.  8,  1906 . 

0.9733 

+31°  45' 

Dec.  18,  1906 . 

0.9730 

+31°  25' 

Jan.  4,  1907 . 

0.9737 

+31°  0' 

1.07 

0.37 

0.89 

Feb.  12,  1907 . 

0.9828 

+31°  15' 

2.03 

0.71 

1.70 

Mar.  15,  1907 . 

0.9744 

+31°  25' 

3.35 

1.17 

2.84 

Apr.  15,  1907 . 

0.9755 

+31°  35' 

3.35 

1.17 

2.84 

May  15,  1907 . 

0.9748 

+31°  43' 

3.26 

1.14 

2.74 

[54] 


SIEVERS— ADDITIVE  CAPACITY  OF  LTNSATTJRATED  HYDROCARBONS 


[55] 


Time  w  Months 


18 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


TABLE  III 

1  Volume  of  Limonene  +  1  Volume  of  Acid  +  1.11  Gms.  of  HC1 


Date 

O 

0 

© 

o 

Ester  No. 

p.  C.  Of 
ester 

p.  c.  as 
ester 

1906 

Nov.  29 . 

0.9390 

+47°  35' 

Dec.  8 . 

0.9389 

+48°  00' 

’ 

Dec.  18 . 

0.9390 

+47°  40' 

1907 

Jan.  4 . 

0.9403 

+47°  20' 

3.00 

1.08 

1.68 

Feb.  12 . 

0.9430 

4-46°  40' 

3.50 

1.22 

1.92 

Mar.  15 . 

0.9402 

+47°  38' 

5.41 

1.89 

2.93 

Apr.  15 . 

0.9441 

+47°  34' 
+46°  45' 

4.20 

1.47 

2.28 

May  15 . 

0.9408 

5.09 

1.78 

2.78 

TABLE  IV 

1  Volume  of  Limonene  +  2  Volumes  of  Acid  +  1.11  Gms.  of  HC1 


Dat© 

<D>20° 

(^20° 

Ester  No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

1906 

Nov.  29 . 

0.9742 

+31°  50' 

T)fip..  8 . 

0.9740 

+31°  37' 

Dec.  18 . 

0.9740 

+31°  20' 

1907 

Jan.  4 . 

0.9750 

+31°  30' 

2.65 

0.92 

2.23 

Feb.  12 . 

0.9746 

+31°  15' 

3.61 

1.26 

8.04 

Mar.  15 . 

0.9750 

+31°  20' 

3.73 

1.30 

3.14 

Apr.  15 . 

0.9764 

+31°  35' 

3.92 

1.37 

3.30 

May  15 . 

0.9754 

+31°  25' 

4.49 

1.57 

3.78 

[56] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  19 


[57 


Time  inhontfis. 


20 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


TABLE  V 

1  Vol.  ofLimonene-(-1  Vol.  of  AciD-f-2.5  Gms.  of  Anhyd.  Na  OCOCHs 


Date 

(D>2o° 

(a) 

;20° 

Ester  No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

1906 

Nov.  29 . 

0.9414 

+47°  40' 

Dec.  8 . 

0.9416 

+47°  37' 

Dec.  18 . 

0.9430 

+46°  45' 

1907 

Jan.  4 . 

0.9440 

+46°  25’ 

2.21 

0.77 

1.26 

Feb.  12 . 

0.9453 

+46°  15' 

4.32 

1.51 

2.35 

Mar.  15 . 

0.9464 

+46°  0' 

5.32 

1.86 

2.88 

Apr.  15 . 

0.9482 

+45°  50' 

6.49 

2.27 

3.55 

May  15 . 

0.9490 

+45°  15' 

9.47 

3.32 

5.19 

TABLE  VI 

1  Vol.  of  Limonene  +  2  Yols.  of  Acid+2.5  Gms.  of  Anhyd.  Na  OCOCHs 


Date 

( D)gQo 

(ar)20° 

Ester 

No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

1906 

Nov  29 

0.9758 

0.9764 

0.9767 

0.9758 

+31°  50' 
+31°  40' 
+31°  30' 

+31°  4' 

Dec  8 

Dec  18 

1907 

Jan.  4 . 

1.40 

0.49 

1.18 

Feb.  12 . 

0.9770 

+31°  20' 

2.85 

0.99 

2.40 

Mar.  15 . 

0.9785 

+31°  0' 

3.73 

1.30 

3.15 

Apr.  15 . 

0.9800 

+31°  5' 

3.94 

1.38 

3.33 

May  15 . 

0.9798 

+31°  12' 

6.75 

2.36 

.5.70 

[58] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  21 


JO 


Time  m  Months 


22 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


Formation  of  Esters  at  Higher  Temperatures  and 
Under  Increased  Pressure 

In  order  to  determine  the  effect  of  higher  temperature  and 
increased  pressure  the  following  experiments  were  conducted: 
Two  mixtures  of  pinene  and  glacial  acetic  acid,  one  containing 
equal  volumes  of  both,  and  the  other  one  volume  of  pinene  and 
two  volumes  of  the  acid,  were  placed  in  small  pressure  bottles 
and  heated  in  a  water  bath.  After  heating  for  eight  hours  the 
physical  constants  and  ester  content  were  determined.  Fresh 
mixtures  were  then  heated  under  the  same  conditions  for  sixteen 
hours  and  the  physical  constants  and  ester  content  again  de¬ 
termined.  Finally  similar  mixtures  were  heated  for  twenty-four 
hours. 

The  temperature,  100°  C.,  applied  in  this  case  was  below  the 
boiling  point  of  the  mixture,  and  as  the  amount  of  ester  obtained 
was  not  very  great,  further  experiments  were  performed  with 
the  same  material  in  which  higher  temperatures  were  applied. 
In  this  case  the  bottles  containing  the  mixtures  were  heated  in 
an  oil-bath  at  a  temperature  ranging  from  140° -150°  C.  This 
temperature  was  chosen  because  it  is  above  the  boiling  point  of 
the  glacial  acetic  acid  and  also  above  that  of  the  mixture,  whereas 
it  is  below  that  of  the  pinene.  The  time  of  heating  was,  as  in 
the  previous  experiments,  eight,  sixteen,  and  twenty-four  hours 
respectively. 

The  mixtures  heated  at  the  higher  temperatures  acquired  a 
light  straw  color  when  heated  for  sixteen  hours  and  a  decided 
yellow  color  when  heated  for  twenty-four  hours. 

The  following  tabulation  shows  the  results  obtained  in  the 
three  different  series  of  experiments. 


[60] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  23 


TABLE  I.  100°  C 

1  Volume  of  Pinene  -f*  1  Volume  of  Acid 


Time 

8 

to-" 

o 

(<3^)20° 

Ester  No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

8  hrs . 

0.9465 

+4°  25' 

10.18 

3.77 

5.80 

16  hrs . 

0.9488 

+3°  36' 

13.80 

4.83 

7.42 

24  hrs . 

0.9502 

+3°  40' 

15.54 

5.44 

8.37 

1  Volume  of  Pinene  -f~  2  Volumes  of  Acid 


8  hrs . 

0.9807 

+2°  33' 

10.30 

3.60 

8.58 

16  hrs . 

0.9823 

+2°  33' 

14.43 

5.05 

12.10 

24  hrs . 

0.9838 

+2°  36' 

15.70 

5.49 

13.12 

TABLE  II.  140°  to  150°  G 

1  Volume  of  Pinene  +  1  Volume  of  Acid 


Time 

^20° 

(a\o° 

Ester  No. 

p.  C.  Of 
ester 

p.  c.  as 
ester 

8  hrs . 

0.9590 

+4°  24' 

34.50 

12.09 

18.78 

16  hrs . 

0.9586 

+4°  0' 

40.90 

14.30 

22.26 

24  hrs . 

0.9568 

+3°  52' 

34.92 

12.21 

18.90 

1 

Volume  of 

Pinene  -f-  2 

Volumes  of  Acid 

8  hrs . 

0.9962 

+2°  35' 

30.10 

10.52 

25.50 

16  hrs . 

0.9921 

+2°  20' 

29.45 

10.30 

24.80 

24  hrs . 

0.9881 

+1°  30' 

30.20 

10.58 

25.40 

TABLE  III.  175°  to  185°  C 

1  Volume  of  Pinene  +  1  Volume  of  Acid 


Time. 

8 

0 

O 

(a)2o° 

Ester  No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

8  hrs . 

0.9517 

+3°  0' 

21.12 

7.39 

11.5 

16  hrs . 

0.9509 

+3°  25' 

39.4 

13.8 

21.00 

24  hrs . 

0.9581 

+3°  18' 

35.10 

12.13 

19.1 

1  Volume  of  Pinene  +  2  Volumes  of  Acid 


8  hrs . 

0.9895 

+2°  37' 

26.58 

9.31 

11.5 

16  hrs . 

0.9873 

+3°  3' 

26.1 

9.14 

21.97 

24  hrs . 

0.9876 

+1°  23' 

30.10 

10.52 

25.3 

[61] 


24 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


[62] 


T/rrte  trt  Hours. 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  25 


ESTER  FORMATION  UNDER  ORDINARY  PRESSURE 

The  preceding  experiments  show  the  extent  of  ester  formation 
when  the  mixtures  are  heated  in  sealed  tubes  at  various  tem¬ 
peratures  and  for  various  intervals  of  time.  In  order  to  study 
the  effect  of  the  time  of  heating  under  normal  pressure  the 
following  series  of  experiments  were  conducted.  300  cc.  of  a 
mixture  of  equal  parts  of  pinene  and  glacial  acetic  acid  were 
placed  in  a  round  bottomed  flask  of  one  liter  capacity  and  con¬ 
nected  with  a  reflux  condenser.  The  mixture  was  heated  slowly 
up  to  its  boiling  point  when  the  heat  was  removed  long  enough 
to  take  a  small  sample  from  the  flask.  The  heating  was  then 
continued  for  fifteen  minutes  when  another  sample  was  removed. 
In  this  way  the  experiment  was  continued,  samples  being  taken 
out  at  definite  intervals,  such  intervals  being  gradually  increased 
as  the  heating  continued.  Towards  the  last  the  samples  were 
taken  out  every  two  hours.  Altogether  the  mixture  was  heated 
twenty  hours.  As  the  heating  proceeded  the  material  in  the 
flask  gradually  darkened  and  at  the  close  of  the  period  had 
acquired  a  dark  brown  color. 

The  samples  taken  out  in  each  case  were  just  enough  for  one 
ester  determination.  No  duplicate  could  therefore  be  made; 
neither  could  the  specific  gravity  and  angle  of  rotation  be  taken 
of  each  sample.  The  specific  gravity  and  optical  rotation  of  the 
mixture  before  heating  were  taken  and  found  to  be  as  follows, 
viz.:  sp.  gr.  at  20°=0.9400;  angle  of  rotation  at  20°=+8°  40'. 

After  heating  for  twenty  hours  the  specific  gravity  was  found 
to  be  0.9529  at  20°  C.  The  optical  rotation  could  not  be  taken 
on  account  of  the  dark  color  of  the  mixture. 

An  exact  duplicate  of  this  experiment  was  made  with  a  mixture 
of  one  volume  of  pinene  and  two  volumes  of  glacial  acetic  acid. 
Samples  were  taken  out  at  exactly  the  same  intervals  and  the 
heating  carried  out  under  exactly  the  same  conditions.  In  this 
case  again  the  mixture  gradually  turned  dark  and  after  twenty 
hours  of  heating  it  also  was  of  a  dark  reddish-brown  color, 
slightly  darker,  however,  than  the  preceding  mixture. 


26 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


The  physical  properties  before  heating  were  as  follows :  specific 
gravity  at  20°  C.=  0.9743';  optical  rotation  at  20°  C.  =+6°  8'. 
After  heating  the  specific  gravity  was  0.9888.  Here  again  the 
optical  rotation  could  not  be  taken  on  account  of  the  dark  color 
of  the  mixture. 

The  boiling  point  of  the  first  mixture  was  116.5°  C.  and  that 
of  the  second  was  116°  C.  In  both  cases  the  boiling  point  rose 
very  gradually  through  about  one  degree  during  the  process  of 
heating. 

The  following  is  a  tabulation  of  the  ester  number,  percentage 
of  ester,  and  percentage  of  pinene  as  ester  in  each  sample.  In 
order  to  calculate  the  true  percentage  of  pinene  as  ester  in  the 
mixture  it  is  necessary  to  know  the  specific  gravity  in  each  case. 
Since  the  specific  gravity  was  not  taken  in  each  case  the  average 
of  the  specific  gravities  of  the  mixtures  before  and  after  heating 
was  used  in  the  calculations.  It  must  therefore  be  borne  in 
mind  that  the  percentage  as  tabulated  below  is  only  a  very  close 
approximation.  The  average  specific  gravity  of  the  first  mixture 
was  0.9464  at  20° ;  that  of  the  second  was  0.9815  at  20°. 


Time 

1  Volume  of  Pinene  +  1  Vol¬ 
ume  of  Acid 

1  Volume  of  Pinene  +  2  Vol¬ 
umes  OF  ACID 

Ester  No. 

p.  C.  Of 
ester 

p.  c.  as 
ester 

Ester  No. 

p.  c.  of 
ester 

p.  c.  as 
ester 

2.56 

0.89 

1.37 

2.90 

1.01 

2;39 

15  min . 

3.71 

1.29 

1.99 

9.04 

3.16 

7.46 

30  min . 

5.51 

1.93 

2.96 

45  min . 

7.29 

2.55 

3.91 

11.87 

4.16 

9.81 

1  hr . 

9.01 

3.15 

4.82 

10.60 

3.71 

8.75 

1:15 . 

19.63 

3.36 

5.16 

10.90 

3.81 

8.99 

1:30 . 

11.95 

4.20 

9.90 

2  hrs . 

12.53 

4.38 

6.71 

2:30 . 

13.30 

4.65 

7.13 

13.50 

4.73 

11.15 

3  hrs . 

17.32 

6.05 

9.28 

15.60 

5.46 

12.90 

4  hrs . 

16.80 

5.89 

9.02 

19.70 

6.90 

10.30 

6  hrs . 

19.60 

6.86 

10.51 

22.00 

7.70 

18.20 

8  hrs . 

22.60 

7.91 

12.10 

23.05 

8.05 

19.00 

10  hrs . 

28.30 

9.55 

14.63 

23.00 

8.05 

19.00 

12  hrs . 

29.30 

10.24 

15.70 

26.80 

9.36 

22.18 

14  hrs . 

31.10 

10.84 

16.68 

26.80 

9.39 

22.18 

16  hrs . 

38.60 

13.32 

20.70 

26.78 

9.37 

22.10 

18  hrs . 

38.05 

13.31 

20.40 

25.20 

8.82 

20.80 

20  hrs . 

36.60 

12.81 

19.61 

30.00 

10.50 

24.80 

[64] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  27 


[65] 


ut 


28 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


ADDITION  OF  PICRIC  ACID  TO  PINENE 

Bornyl  picrate  was  prepared  according  to  Tilden  and  Forster  4 
in  the  following  way:  20  gms.  of  chemically  pnre  picric  acid 
w7ere  mixed  with  200  cc.  of  rectified  turpentine  oil  in  a  round 
bottomed  liter  flask  connected  with  a  reflux  condenser.  No  re¬ 
action  was  observed  in  the  cold,  and  the  acid,  being  insoluble 
in  the  turpentine  oil,  settled  at  the  bottom.  The  temperature  was 
slowly  raised  by  means  of  a  low  flame.  As  the  temperature  rose 
the  mixture  gradually  acquired  a  reddish  color  which  changed 
to  dark  red-brown  when  150°  was  reached.  At  this  temperature 
the  mixture  began  to  crack  and  the  evolution  of  heat  was  almost 
sufficient  to  keep  the  temperature  at  150°  without  the  aid  of  a 
flame.  After  heating  for  about  one  hour  the  mixture  was  al¬ 
lowed  to  cool  somewhat,  after  which  the  liquid  portion  was 
poured  into  a  beaker  and  set  aside  in  a  cool  place  to  crystallize. 
The  black  tarry  residue  which  remained  in  the  flask  was  examined 
later. 

After  about  twelve  hours  small  clusters  of  crystals  began  to 
form  on  the  sides  of  the  beaker  containing  the  liquid,  and  after 
twenty-four  hours  the  crystallization  was  interrupted,  the  mother 
liquid  set  aside  for  further  crystallization,  and  the  crystals  re¬ 
moved  for  purification.  On  the  bottom  of  the  beaker  was  a 
layer  of  tarry  material  resembling  that  which  remained  in  the 
original  flask. 

The  crystals  were  rubbed  in  a  mortar  with  several  portions  of 
water  to  remove  the  picric  acid.  They  were  then  transferred  to 
a  flask  and  boiled  with  alcohol  until  all  were  dissolved.  Upon 
cooling  the  crystals  again  separated  in  the  form  of  small  yellow 
scales.  After  draining  on  a  force  filter  and  washing  several 
times  with  small  portions  of  alcohol,  the  crystals  were  allowed  to 
dry  and  were  then  transferred  to  a  bottle. 

Upon  standing  in  diffused  daylight  the  crystals  soon  became 
darker  in  color,  changing  from  a  bright  yellow  to  a  yellowish- 


4  Journ.  Am.  Ghem.  Soc.,  1893  I,  p.  1388. 


•SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  29 

brown.  That  side  of  the  bottle  which  was  exposed  to  the  direct 
light  of  the  window  changed  color  much  more  quickly. 

The  mother  liquid,  after  standing  for  several  hours,  showed  no 
signs  of  further  crystallization  and  was  therefore  taken  and 
distilled  with  steam.  A  colorless  oily  layer  separated  from  the 
aqueous  distillate.  This  material  which  had  a  distinct  pinene 
odor  was  separated  and  fractionated.  It  distilled  at  a  tempera¬ 
ture  ranging  from  150°  to  159°  C.,  the  bulk  of  it  distilling  at 
155°  to  157°.  The  specific  gravity  of  the  main  fraction  was 
found  to  be  0.8599  at  20°  C.  and  the  angle  of  rotation  was 
+5°  40'. 

Judging  from  the  odor,  boiling  point,  and  specific  gravity,  the 
material  was  pinene  with  a  greatly  reduced  optical  activity. 

Saponification  of  the  “Ester” 

The  bornyl  picrate  was  mixed  with  a  molecular  quantity  of 
potassium  hydroxide  in  alcohol  and  boiled  on  a  water  bath  for 
about  one  hour.  The  mixture  turned  to  a  dark  brown  color 
After  cooling,  the  material  was  distilled  with  steam.  The  first 
distillate  consisted  mainly  of  alcohol  with  a  strong  camphoracous 
odor.  Upon  further  distillation  small  crystals  began  to  separate 
on  the  sides  of  the  flask  and  condenser  and  also  in  the  receiver. 
After  no  more  crystals  came  over  the  distillation  was  stopped 
and  the  borneol  collected  and  drained  on  a  filter.  It  consisted 
of  fine  white  crystals. 


ACTION  OF  GLACIAL  ACETIC  ACID  ON  AMYLENE 

In  order  to  ascertain  whether  esters  of  the  unsaturated  hydro¬ 
carbons  of  the  olefine  series  could  be  obtained  in  like  manner,  the 
action  of  glacial  acetic  acid  on  amylene  was  tried. 

The  amylene  used  was  optically  inactive  and  had  a  specific 
gravity  of  0.6779  at  20°  C.  A  mixture  of  equal  volumes  of  amy¬ 
lene  and  glacial  acetic  acid  had  a  specific  gravity  of  0.8639  at 
20°  C.  immediately  after  mixing.  A  mixture  of  one  volume  of 
amylene  and  two  volumes  of  glacial  acetic  acid  had  a  specific 
gravity  of  0.9250  at  20°  C. 


30 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


After  standing  for  just  one  month  the  ester  content  was  de¬ 
termined  by  means  of  a  method  similar  to  that  used  for  the 
other  mixtures. 

1  Volume  Amylene  +  1  Volume  Glacial  Acetic  Acid 


Date 

(D)20o 

Ester  No. 

p.  c.  of  ester 

p.  c.  as  ester 

May  20,  1907 . 

0.864 

12.86 

2.97 

7.90 

1  Volume  Amylene  +  2  Volumes  Glacial  Acetic  Acid 

May  20,  1907 . 

0.9253 

7.97 

1.85 

7.58 

CONCLUSIONS 

In  summarizing  the  facts  brought  out  by  the  foregoing  ex¬ 
periments  one  appears  especially  significant,  namely  the  influence 
of  the  mass.  In  every  experiment  performed  this  is  clearly 
brought  out.  The  percentage  of  hydrocarbon  changed  to  ester 
is,  with  one  exception,  appreciably  higher  in  each  case  where  the 
amount  of  the  acid  is  doubled.  In  the  curves  accompanying 
these  data,  curve  A  shows  in  each  case  the  results  obtained  from 
one  volume  of  the  hydrocarbon  with  one  volume  of  the  acid,  and 
curve  B  the  results  obtained  from  one  volume  of  the  hydrocarbon 
with  2  volumes  of  the  acid.  A  study  of  the  curves  will  show 
that,  with  one  exception,  the  percentage  of  the  hydrocarbon 
changed  to  ester  in  mixture  B  is  considerably  higher  than  in 
mixture  A.  This  increase  in  ester  is  apparent  in  the  very  first 
observation  made  and  continues  to  be  so  throughout  the  entire 
time  of  observation  extending  through  several  months. 

Whereas  the  amount  of  the  acid  in  B  in  these  experiments 
was  only  twice  that  in  A,  it  is  reasonable  to  suppose  that  a  greater 
increase  in  the  ratio  of  acid  to  hydrocarbon  may  lead  to  a  still 
higher  percentage  of  addition  products  formed.  However,  this 
has  still  to  be  proven  experimentally.  It  seems  safe  to  say,  how¬ 
ever,  even  from  the  few  observations  made  in  regard  to  the  in¬ 
fluence  of  mass  action,  that,  to  secure  a  yield  of  ester  which  would 
be  of  any  practical  commercial  value,  the  significance  of  mass 

[68] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  3J 

influence  is  a  very  important  one,  and  one  which,  will  be  deserv¬ 
ing  of  careful  consideration. 

In  the  experiments  with  limonene  not  only  the  influence  of 
mass  action  was  observed,  but  also  the  influence  of  so-called 
catalytic  agents.  Anhydrous  sodium  acetate  has  long  been  em¬ 
ployed  in  the  acetylization  of  volatile  oils  by  means  of  acetic  acid 
anhydride.  Just  what  its  action  is  in  such  cases  has  never  been 
satisfactorily  explained.  The  fact  remains,  however,  that  it  in¬ 
sures  a  more  complete  esterification.  It  was  interesting,  there¬ 
fore,  to  try  its  action  in  these  experiments,  where  we  have  ester 
formation,  not  by  the  action  of  an  acid  on  alcohol  as  is  supposed 
to  be  the  case  in  volatile  oils,  but  by  direct  addition.  If  in  this 
case  an  increase  of  ester  could  be  observed  due  to  the  presence 
of  such  a  reagent  then  a  similar  significance  might  be  attached 
to  its  use  in  the  determination  of  alcohols  in  volatile  oils. 

Another  so-called  catalytic  agent  used  was  anhydrous  hydro¬ 
gen  chloride.  The  mixtures  of  limonene  and  glacial  acetic  acid 
were  exactly  the  same  in  each  case  and  differed  only  in  the  pres¬ 
ence  of  these  so-called  catalytic  agents.  Any  difference  in  the 
percentage  of  hydrocarbon  changed  to  ester  can  therefore  only 
be  accounted  for  by  the  action  of  these  agents. 

In  studying  the  curves  plotted  from  the  data  obtained  from 
these  experiments  some  extremely  interesting  results  are  brought 
out.  The  data  thus  far  recorded  have  been  obtained  from  ob¬ 
servations  extending  over  approximately  five  months.  The  first 
set  of  curves  shows  the  amount  of  limonene  changed  to  ester 
when  standing  in  contact  with  glacial  acetic  acid  alone.  In  five 
months  a  maximum  of  2.84  p.  c.  was  obtained.  The  second  set 
of  curves  shows  the  influence  of  the  anhydrous  hydrogen  chloride. 
In  this  case  a  maximum  of  3.78  p.  c.  was  obtained.  The  third 
set  of  curves  shows  the  influence  of  the  anhydrous  sodium  ace¬ 
tate.  Here  a  maximum  of  5.71  p.  c.  was  observed.  Thus  we 
have  a  difference  of  2.86  p.  c.  due  to  apparently  no  other  cause 
than  the  influence  of  the  sodium  acetate,  and  an  increase  of  0.94 
p.  c.  due  to  the  influence  of  the  hydrogen  chloride.  Thus  with 
sodium  acetate  we  have  a  percentage  of  ester  which  is  a  trifle 
more  than  twice  that  in  a  similar  mixture  but  without  the  so- 
called  catalytic  agent.  From  these  results  it  becomes  evident 

[69] 


32 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


that  both  the  so-called  catalytic  agents  used  have  a  tendency  to 
increase  the  additive  capacity  of  the  hydrocarbon,  and  that 
sodium  acetate  has  by  far  the  greater  influence  of  the  two.  An 
interesting  observation  that  should  be  made  here  is  the  relation 
of  the  presence  of  sodium  acetate  to  mass  action.  It  will  be  ob¬ 
served  in  the  first  two  sets  of  curves  that  mixture  B  shows  a 
considerable  increase  in  percentage  over  A.  In  the  curves  for 
the  mixtures  containing  sodium  acetate,  however,  both  show  very 
nearly  the  same  extent  of  ester  formation.  This  is  true  through¬ 
out  the  entire  period  of  observation.  The  influence  of  mass  ac¬ 
tion  is  apparently  lost  here. 

The  experiments  performed  to  show  the  influence  of  higher 
temperatures  and  pressure  on  the  amount  of  ester  formed  bring 
out  many  points  of  interest.  From  the  curves  it  can  be  seen 
that  the  greatest  addition  takes  place  during  the  first  eight  hours 
of  heating.  This  is  especially  true  where  higher  temperatures 
than  100°  are  employed.  After  heating  16  hours  there  is  ap¬ 
parently  little  or  no  increase  in  the  addition  products  formed; 
in  fact  in  some  cases  there  is  a  decrease  as  the  curves  indicate. 
In  the  mixtures  containing  one  volume  of  pinene  to  two  volumes 
of  glacial  acetic  acid  we  practically  reach  the  maximum  per¬ 
centage  after  the  first  eight  hours  of  heating. 

It  must  be  borne  in  mind,  however,  that  in  these  experiments 
we  have  entirely  different  conditions  than  in  those  where  the 
time  of  contact  alone  becomes  a  factor.  The  high  temperatures 
and  the  correspondingly  high  pressure  under  which  these  data 
were  obtained  doubtless  give  rise  to  reactions  other  than  the 
mere  addition  of  the  acid  to  the  ester- forming  hydrocarbon. 
Thus  there  may  be  a  change  of  the  hydrocarbon  pinene  to  its 
isomer  limonene,  or  other  similar  reactions.  The  assumption 
that  such  varied,  and  possibly,  highly  complex  changes  take 
place  under  the  existing  conditions  gains  weight  from  the  fact 
that  the  physical  constants  of  these  mixtures  undergo  extensive 
changes  under  this  treatment.  These  changes  seem  to  occur  with 
no  apparent  regularity  as  is  the  case  with  the  mixtures  standing 
in  simple  contact  at  room  temperature. 

Viewed  from  a  practical  standpoint,  it  at  once  becomes  ap¬ 
parent  that  there  is  no  material  advantage  in  prolonging  the 

I  [70] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  33 

time  of  heating.  From  the  data  obtained  thns  far  it  seems  safe 
to  say  that  sixteen  hours  would  be  quite  sufficient.  As  far  as  the 
change  of  the  hydrocarbon  to  ester  is  concerned,  the  greatest 
efficiency  is  obtained  by  heating  one  volume  of  pinene  with  two 
volumes  of  glacial  acetic  acid  at  175°  to  185°  for  a  period  of 
about  eight  hours. 

The  experiments  conducted  with  the  object  of  determining  the 
influence  of  increased  pressure  on  the  amount  of  ester  formation 
have  proved  of  very  great  importance.  The  results  have  dem¬ 
onstrated  without  doubt  that  any  increase  over  normal  atmos¬ 
pheric  pressure  and  any  temperature  above  the  boiling  point  is 
of  no  material  advantage.  Thus  the  maximum  percentage  of 
hydrocarbon  changed  to  ester  at  175°  to  185°  is  a  trifle  over  25 
per  cent  after  heating  for  24  hours,  while  the  maximum  per¬ 
centage  obtained  when  boiling  a  similar  mixture  under  ordinary 
pressure  for  20  hours  is  24.8  per  cent.  This  result  when  viewed 
from  a  practical  standpoint  is  of  great  significance.  Whereas 
the  last  experiment  is  easily  conducted,  the  first  involves  numer¬ 
ous  technical  difficulties,  at  least  when  conducted  on  a  large 
scale. 

One  of  the  objects  in  view  when  these  experiments  were  begun 
was  to  determine  to  what  extent  the  amount  of  ester  formation 
would  be  indicated  by  the  physical  constants.  In  the  long  series 
of  observations  on  pinene  with  acetic  acid  some  interesting  points 
have  been  brought  out  in  regard  to  the  changes  in  physical  con¬ 
stants.  The  changes  were  very  gradual  but  after  seven  or  more 
months  of  observation,  it  is  found  that  the  specific  gravity  has 
increased  and  the  angle  of  rotation  has  decreased  in  both  mix¬ 
tures.  With  a  few  exceptions,  due  probably  to  experimental 
error,  these  changes  have  proceeded  with  fair  regularity  in  both 
mixtures. 

In  the  experiment  with  limonene  we  again  find  the  specific 
gravity  slowly  increasing  with  the  time  of  contact.  This  is 
especially  true  in  cases  where  the  so-called  catalytic  agents  have 
been  used.  The  optical  activity,  however,  does  not  show  any 
changes  in  any  definite  direction.  In  the  experiments  where 
higher  temperatures  and  pressure  are  employed  the  physical  con¬ 
stants,  as  has  been  mentioned  previously,  change  back  and  forth 

[71]  \ 


34 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


without  any  regularity  whatsoever.  Taken  as  a  whole  the 
changes  in  the  physical  constants  seem  to  be  too  small  to  serve 
as  a  valuable  criterion  in  regard  to  the  amount  of  ester  present. 

Finally,  in  summarizing  the  results  which  these  experiments 
have  brought  out,  it  must  become  apparent  that  the  matter  under 
investigation  is  of  sufficient  interest,  both  practically  as  well  as 
theoretically,  to  warrant  a  further  systematic  study  of  the  sub¬ 
ject.  In  the  work  here  recorded  only  the  action  of  acetic  acid 
has  been  studied,  but  the  investigation  of  the  action  of  other 
organic  acids  appears  fully  as  promising. 


OBSERVATIONS  AND  CONCLUSIONS  AFTER  TWO  AND 
ONE-HALF  YEARS 

The  investigations  recorded  in  the  foregoing  pages  were  tem¬ 
porarily  brought  to  a  close  in  June,  1907.  The  different  mix¬ 
tures  of  hydrocarbons  and  acids  which  had  been  used  were  care¬ 
fully  set  aside  to  be  examined  again  some  time  in  the  future,  if 
the  opportunity  presented  itself.  Such  an  opportunity  came  in 
December,  1909,  two  and  one-half  years  later.  The  mixtures 
were  again  examined  as  to  specific  gravity,  angle  of  rotation,  and 
the  amount  of  esterification.  The  esters  were  determined  in  the 
same  way  as  in  the  earlier  examinations.  In  order  to  show  the 
changes  that  had  taken  place  in  these  mixtures  since  their  last 
previous  examination,  the  following  tabulation  is  appended 
which  shows  the  results  of  the  last  examination  in  1907,  and  the 
recent  one  in  December,  1909. 


PlNENE  AND  GLACIAL  AcETIC  ACID 


1  Vol.  of  Pinene  + 1  Vol.  of  Acid 

1  Vol.  of  Pinene  +  2  Vols.  of  Acid 

Date 

D 

(dr) 
v  '20° 

p.  c.  of  pin¬ 

D 

(a) 

p.  c.  of  pin¬ 

20° 

ene  as  ester 

20° 

v  20° 

ene  as  ester 

May  15,  1907... 

0.9502 

+7°  18' 

7.40 

0.9804 

+4°  15' 

9.05 

Dec.  7,1909.... 

0.9590 

+3°  15' 

18.30 

0.9960 

+2°  15' 

28.70 

[72] 


SILVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  35 


Limonene  and  Glacial  Acetic  Acid 


1  Vol.  of  Limonene  +  1  Vol.  of  Acid 

1  Vol.  of  Limonene+2  Vols.  of  Acid 

Date 

p.  c.  limo¬ 

d20° 

(a)2o° 

p.  c.  limo¬ 

■D20° 

i 

(«)20° 

nene  as 
ester. 

nene  as 
ester. 

May  15,  1907. 

0.9400 

+47°  0' 

2.06 

0.9748 

+31°  43' 

2.74 

Dec.  7,  1909. 

0.9470 

+38°  39' 

12.90 

0.9880 

+28°  42' 

10.07 

Limonene  and  Glacial  Acetic  Acid  and  Anhydrous  Hydrogen  Chloride 


1  Yol.  of  Limonene  +1  Vol.  of  Acid 

1  Vol.  of  Limonene  +  2  Vols.  of  Ac. 

+  1.11  gms.  of  H  Cl. 

+ 1.11  gins,  of  H  Cl. 

Date 

O 

O 

! 

p.  c.  limo¬ 

D20° 

(tf)20° 

p.  c.  limo¬ 

d20° 

nene  as 

nene  as 

ester 

ester 

May  15,  1907. 

0.9408 

+46°  45' 

2.78 

0.9754 

+31°  25' 

3.78 

Dec.  7,  1909. 

0.9430 

+46°  16' 

7.47 

0.9770 

+30°  20'. 

9.39 

Limonene  and  Glacial  Acetic  Acid  and  Anhydrous  Sodium  Acetate 


Date 

1  Vol.  of  Lim.  +  1  Vol.  of  Acid  +  2.5 
gms.  of  NaOCOCHs 

1  Vol.  of  Lim.  +  2  Vols.  of  Acid  +  2.5 
gms.  of  Na  OOOCH3 

d20° 

(a)20° 

p.  c.  limo¬ 
nene  as 
ester 

d20° 

(g02o° 

p.  c.  limo¬ 
nene  as 
ester 

May  15,  1907. 
Dec.  7,  1909. 

0.9490 

0.9700 

+45°  15' 
+35°  45' 

5.19 

33.30 

0.9798 

0.9870 

+31°  12' 
+28°  58' 

5.70 

15.95 

Amylene  and  Glacial  Acetic  Acid 


Date 

1  Vol.  of  Amylene +  1  Vol.  of  Acid 

1  Vol.  Amylene  +2  Vols.  Acid 

d20° 

p.  c.  amy¬ 
lene  as 
ester 

D2qo 

p.  c.  amy¬ 
lene  as 
ester 

May  20,  1907. 
Dec.  7,  1909. 

0.8640 

0.9560 

7.90 

23.00 

0.9253 

0.9910 

7.58 

33.80 

[73] 


36 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


Taken  as  a  whole  the  changes  which  have  taken  place  in  these 
mixtures  in  the  last  two  and  one-half  years  have  been  largely  in 
the  direction  indicated  by  the  observations  made  during  the 
first  five  months.  In  the  mixtures  of  pinene  and  glacial  acetic 
acid  the  specific  gravity  has  continued  to  increase  very  gradually 
while  the  angle  of  rotation  has  decreased  to  about  one-half  in 
both  mixtures.  The  amount  of  esters  has  also  very  materially 
increased. 

In  the  mixtures  of  limonene  and  glacial  acetic  acid  similar 
changes  as  indicated  in  the  pinene  mixtures  have  taken  place 
but  to  a  much  smaller  extent.  In  those  mixtures  containing 
hydrogen  chloride  as  a  catalytic  agent  the  changes,  though  in 
the  same  direction  as  indicated  previously  have  been  very  small 
indeed.  A  much  higher  formation  of  esters  and  a  correspond¬ 
ingly  greater  change  in  the  physical  constants  has  taken  place 
in  the  mixture  of  limonene  and  acetic  acid  containing  anhydrous 
sodium  acetate.  This  is  especially  true  where  equal  parts  of 
acid  and  hydrocarbon  are  used.  It  seems  that  here  the  catalytic 
action  of  the  sodium  acetate  has  exerted  a  very  strong  influence. 
The  mixtures  of  amylene  and  acetic  acid  show  a  very  consider¬ 
able  increase  in  specific  gravity  and  a  large  amount  of  ester. 

In  commenting  on  the  results  obtained  in  the  first  few  months, 
attention  was  directed  to  the  apparent  influence  of  mass  action. 
The  extent  of  ester  formation  was  in  almost  every  case  greater 
where  the  amount  of  the  acid  was  doubled.  This  influence  of 
mass  action  is  much  less  evident  after  the  recent  examination. 
Yet  it  remains  apparent  in  the  mixtures  of  pinene  and  acetic 
acid,  in  the  mixtures  of  limonene  and  acetic  acid  with  the  an¬ 
hydrous  hydrogen  chloride,  and  in  the  mixtures  of  amylene  and 
acetic  acid.  On  the  other  hand  in  the  case  of  limonene  and 
acetic  acid  and  limonene  and  acetic  acid  with  the  anhydrous 
sodium  acetate  the  indication  is  in  the  opposite  direction.  The 
latter  mixture,  even  during  the  first  five  months  showed  that 
the  amount  of  ester  formed,  where  the  volume  of  acetic  acid 
was  doubled,  was  practically  the  same  as  where  equal  volumes 
of  the  acid  and  limonene  were  used.  Now,  after  a  much  longer 
period  of  contact  it  is  found  that  the  mixture  of  equal  volumes 
shows  33.3  p.  c.  of  limonene  changed  to  esters  and  the  mixture 

[74] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATTJRATED  HYDROCARBONS  37 

where  the  acid  was  doubled  only  13.95  p.  c.  In  these  same  mix¬ 
tures  the  higher  per  cent  of  esterification  is  accompanied  by 
a  correspondingly  greater  change  in  the  physical  constants. 
It  seems  then  that  nothing  definite  can  be  said  about  the  in¬ 
fluences  of  mass  action,  especially  in  mixtures  containing  lim- 
onene  to  which  catalytic  agents  have  been  added.  On  the  other 
hand,  in  mixtures  of  pinene  and  also  those  of  amylene  the  effect 
of  mass  action  seems  to  be  quite  clearly  indicated. 

The  physical  constants  show,  on  the  whole,  very  consistent 
changes.  The  specific  gravity  has  steadily  increased  in  all  cases 
and  the  angle  of  rotation  decreased.  It  is  also  seen  that  in  the 
majority  of  cases,  and  this  is  especially  true  of  the  angle  of 
rotation,  the  extent  of  the  change  is  largely  in  proportion  to  the 
•amount  of  ester  formed. 


[75] 


38 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


REVIEW  OP  LITERATURE 

Bouchardat  et  Lafont,  1886.  Sur  Une  Nouvelle  Synthese  D’un 
Borneol  Inactif.  Compt.  Rend.,  102,  p.  171 

A  mixture  of  one  part  of  turpentine  oil  and  one  and  one-half 
parts  of  glacial  acetic  acid  was  heated  for  36  hours  at  100°.  The 
mixture  was  agitated  with  water,  then  with  a  solution  of  an 
alkali  and  finally  submitted  to  fractional  distillation.  The  prod¬ 
ucts  of  the  distillation  were :  pinene  boiling  at  156°  and  another 
product  boiling  at  215°.  Under  the  above  conditions  only  a 
small  amount  of  pinene  is  combined.  If  the  mixture  is  heated 
to  150°  the  reaction  is  greatly  increased,  and  a  substance  boiling 
at  215°  is  obtained.  This  is  the  acetic  ester  of  borneol.  It  is 
a  white  mobile  liquid  with  an  odor  reminding  of  thyme,  op¬ 
tically  inactive,  with  a  specific  gravity  of  0.977  at  0°  C.  Upon 
heating  for  six  hours  in  a  sealed  tube  with  alcoholic  potassa  it  is 
saponified  and  inactive  borneol  is  formed. 

Bouchardat  et  Lafont,  1886.  Sur  L ’action  de  l’acide  Acetique 
Sur  L ’essence  de  Terebenthine.  Compt.  Rend.,  102,  p.  318. 
[Jour.  Chem.  Soc.,  50,  p.  475.] 

In  the  experiments  performed  with  pinene  and  acetic  acid 
the  following  facts  were  brought  out: 

Acetic  acid  combines  with  pinene  in  the  cold  forming  the  mono¬ 
acetates,  belonging  to  two  distinct  series.  At  the  same  time  the 
pinene  not  combined  is  changed  to  two  isomeric  hydrocarbons 
C10  H16,  one  “monovalent,”  i.  e.  “terebenthene,”  with  one  double 
bond;  and  the  other  “bivalent,”  i.  e.  “terpilene,”  with  two  dou¬ 
ble  bonds. 

Bouchardat  et  Lafont,  1886.  Formation  D’alcools  Monoatom- 
iques  Derives  de  L ’essence  de  Terebenthine.  Compt.  Rend., 
102,  p.  433 

From  French  turpentine  two  acetates  were  obtained  with  the 
same  empirical  formulas,  C10H16(C2H4O2),  but  with  widely 
different  properties.  From  these  acetates  the  two  correspond¬ 
ing  alcohols  were  obtained.  Both  alcohols  have  the  formula 

[76] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  39 


C10H18O,  but  their  properties  are  totally  different.  The  method 
of  obtaining  the  acetates  was  as  follows:  The  mixture  of  the 
compounds  resulting  from  the  turpentine  oil  and  acetic  acid 
was  warmed  with  its  weight  of  potassa  and  five  or  six  times  its 
weight  of  alcohol  in  a  sealed  tube  at  100° C.  for  10  hours.  Upon 
the  addition  of  water  an  oily  layer  separated  which  was  purified 
by  redistillation. 

The  following  tabulation  shows  the  acetates  that  were  obtained 
.and  the  products  which  they  yielded  upon  saponfication : 


Acetate  formed 

B.  P  * 

(«)d 

Ale.  formed  on 
saponification 

B.  P* 

<«> 

Cl  oHl  6(C2H40s) . 

Acetate  de  t6r6benthine... . 

95-105° 

105-110° 

+  1°  16' 

Terpilenol . 

Terpilenol 

camphenol 

99-102° 

—17°  24' 

—43°  6' 

Acetate  de  terpilSne . 

110-116° 

Terpilenol . 

99-105° 

Active 

*  Under  diminished  pressure,  ‘  dans  le  vide.” 


From  the  alcohol  obtained  from  the  first  acetate  in  the  table 
a  crystalline  substance  separated  which  was  dried  on  porous 
plate.  It  was  found  to  be  laevogyrate  borneol.  It  is  observed 
that  there  is  a  more  abundant  production  of  laevogyrate  borneol 
than  of  dextrogyrate  borneol. 

Lextrait.  Action  de  L’acide  Picrique  Sur  le  Terebenthene, 
et  sur  le  thymene.  Compt.  Rend.,  102,  p.  555  [Ber.  19,  p. 
237,  Ref.] 

Picric  acid  does  not  act  on  pinene  or  oil  of  turpentine  in  the 
cold,  but  at  150°  vigorous  action  sets  in.  Upon  cooling,  yellow 
crystals  separate  which  can  be  washed  with  hot  alcohol.  These 
crystals  have  the  formula:  C10H16C6H2(NO2)3OII.  The  crystals 
are  insoluble  in  water  but  soluble  in  boiling  alcohol  and  ether. 
Upon  boiling  with  caustic  potash  they  yield  borneol  as  a  white 
precipitate.  This  borneol  has  a  melting  point  199°-200°  and 
boils  at  211°;  aD  — — 37°.  With  HC1  it  gives  a  compound 
decomposible  by  boiling  water;  and  with  nitric  acid  a  substance 
which  corresponds  with  ordinary  camphor  in  odor,  composition, 
boiling  and  melting  point. 


[77] 


40 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


Bouchardat  et  Lafont,  1891.  Action  de  L’acide  Benzoique  Sur 
L ’essence  de  Terebenthine.  Compt.  Rend.,  113,  p.  551 

Benzoic  acid  acts  slowly  on  turpentine  oil  in  the  cold.  Upon 
heating  to  150°  the  reaction  is  more  rapid.  After  heating  for 
50  hours  all  the  oil  is  changed.  It  is  best  not  to  let  the  temper¬ 
ature  go  much  above  150°.  The  operation  is  best  carried  out 
by  heating  in  a  copper  vessel  with  a  reflux  condenser. 

The  products  formed  are  numerous.  Any  excess  of  acid  is 
taken  out  with  an  alkaline  solution.  It  is  then  distilled  up  to 

It  is  supposed  that  the  benzoate  of  pinene  is  first  formed 
which  upon  the  prolonged  heating  decomposes  into  camphene 
and  terpilene. 

200°-220°.  The  products  of  the  fractionation  are: 

1.  Camphene  aD  = — 3°30'  b.  p.  157° 

2.  Terpilene  ^  =  —3°  to  4°30'  b.  p.  175°-180° 

Tilden  and  Forster,  1893.  Preparation  of  Bornyl  Picrate. 
Journ.  Chem.  Soc.,  1893,  1,  p.  1388.  [Ber.  37,  p.  136,  Ref.] 

Picric  acid  is  heated  with  ten  times  its  weight  of  pinene  to 
150°.  The  reaction  keeps  the  temperature  up.  Some  water  is 
produced  and  some  of  the  acid  changes  to  a  tarry  mass.  When 
the  excess  of  the  acid  begins  to  solidify  the  dark  brown  liquid 
is  decanted  into  a  beaker  and  after  several  hours  tufts  of  yellow 
crystals  form.  These  are  washed  with  cold  alcohol,  and  then 
crushed  with  water  in  a  mortar  as  long  as  the  latter  turns  yellow. 
They  are  then  recrystallized  several  times  from  hot  alcohol; 
m.  p.  133°. 

The  picrate  obtained  from  American  turpentine  oil  was 
identical  with  that  obtained  from  French  turpentine.  The  latter 
yielded  a  bomeol  which  was  leavo,  while  the  former  yielded  an 
inactive  bomeol.  When  the  picrate  was  heated  alone  a  distillate 
was  obtained  which  solidified  and  was  found  to  be  camphene; 
m.  p.  47°. 

Bouchardat  et  Tardy,  1895.  Sur  les  Alcools  Derives  d’un  Tere- 
binthene  droit,  L ’eucalyptene.  Compt.  Rend.,  120,  p.  1417. 

Voiry  has  made  known  the  presence  of  small  quantities  of  a 
strongly  dextrogyrate  terpene  in  the  oil  of  Eucalyptus  globulus 
distilled  in  France.  This  terpene,  after  numerous  rectifications, 

[78] 


SIEVERS— ADDITIVE  CAPACITY  OF  UNSATURATED  HYDROCARBONS  44 

had  an  optical  rotation  of  +34°  10'  in  a  100mm  tube.  The  ter- 
pene  obtained  from  the  same  species  of  Eucalyptus  but  from  a 
different  province  was  almost  entirely  inactive.  This  terpene 
is  considered  to  be  a  mixture  of  a  dextro  and  a  levo  terpene 
which  makes  it  entirely  or  almost  entirely  inactive.  A  terpene, 
-40°  30',  was  transformed  into  terpineol  formate  by  acting  on  it 
with  crystallized  formic  acid  in  the  cold.  This  was  then  saponi¬ 
fied  and  upon  distillation  yielded  an  oil  which  solidified  in  a 
freezing  mixture.  The  terpineol  m.  p.  330-34°  thus  prepared 
has  all  the  properties  of  that  obtained  from  laevo-pinene. 

Borneol  and  iso-borneol  were  prepared  from  this  “eucalyp- 
tene”  by  heating  with  benzoic  acid  to  150°.  Most  of  the  ter¬ 
pene  is  changed  to  dextro  limonene.  Another  part  formed  the 
benzoic  ether  of  a  dextro  borneol  and  of  the  optical  isomer  iso- 
borneol  or  fenchoL  The  dextro  borneol  obtained  in  this  method 
possessed  optical  peculiarities  but  rarely  observed  by  the  au¬ 
thor  in  connection  with  the  other  synthetic  bomeols.  Its 
melting  point,  after  numerous  crystallizations  from  petroleum 
ether  and  carbon  disulphide,  was  in  the  neighborhood  of  213°. 
Its  angle  of  rotation  was  +18°  40'  whereas  that  of  the  camphor 
which  it  yielded  was  +31°. 

The  fenchol  or  iso-borneol  obtained  was  separated  by  a  series 
of  distillations  and  crystallizations  Its  m.  p.  was  45°  and  b.  p. 
about  198°-200°.  It  has  all  the  properties  of  iso-borneol  pre¬ 
pared  from  laevo  pinene.  It  furnishes  a  d-camphor  upon  oxida¬ 
tion  which  is  liquid  at  15°,  solid  at  0°.  It  is  strongly  dextro¬ 
gyrate  and  seems  to  be  identical  with  anise  camphor  of  Landolph 
or  the  fenchone  of  Wallach. 

Kriewitz,  O.,  1899.  Ueber  Addition  von  Formaldehyd  an  enige 
Terpene.  Ber.,  32,  p.  57 

Twenty  gms.  of  the  pinene  fraction  of  American  turpentine 
oil,  4.4  gms.  of  paraformaldehyde  and  10  gms.  of  alcohol  are 
heated  in  a  sealed  tube  to  170°-175°  for  about  12  hours.  After 
cooling  water  is  added  and  an  oily  layer  separates  which  is 
shaken  out  with  ether.  Upon  fractionation  a  large  quantity  of 
turpentine  comes  over.  Fraction  225°-240°  is  rectified  with 
steam.  The  oily  distillate  is  shaken  out  with  ether  and  after 


[79] 


42 


BULLETIN  OF  THE  UNIVERSITY  OF  WISCONSIN 


the  evaporation  of  the  ether  the  oil  remaining  is  fractionated  and 
fraction  232°-236°  is  collected.  It  is  a  clear  liquid  of  a  some¬ 
what  thick  consistance  with  an  oder  reminding  of  turpentine. 
It  is  insoluble  in  water  but  soluble  in  ether,  alcohol,  and  ligroin. 
It  is  very  hygroscopic,  strongly  dextrogyrate,  and  has  a  specific 
gravity  of  0.9610  at  20° C.  The  yield  is  very  small,  being  only 
about  15  per  cent,  of  the  pinene  used.  The  compound  was  found 
upon  analysis  to  have  the  formula  C^TT^O.  It  adds  two 
molecules  of  hydrogen  chloride,  hence  is  unsaturated.  That  an 
alcohol  group  results  is  revealed  by  the  formation  of  an  acetyl 
and  a  benzoyl  compound. 

Dextro  limonene  and  dipentene  form  similar  addition  prod¬ 
ucts  with  formaldehyde. 

Wallach,  O.,  1901.  Reobachtungen  in  der  Fenchen  Riehe. 

Ann.  315,  p.  273 

Mix  20  gms.  of  fenchene  with  40  gms.  of  alcohol  and  7  cc.  of 
dilute  sulphuric  acid  and  heat  it  on  a  water  bath  for  some  hours. 
Only  a  small  quantity  of  fenchene  is  recovered  and  in  its  place  a 
number  of  higher  boiling  compounds  are  formed.  Fraction 
200°-201°  was  found  to  have  the  formula  C10H17OC2H5  or  ethyl 
ether  of  iso-fenchyl  alcohol. 


[80] 


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